Aspartame (N-L-a-aspartyl-L-phenylalanine methyl ester) hereinafter referred to as APM, was first described and claimed in U.S. Pat. No. 3,492,131 issued in 1970 by Searle. Since then, it dominates the market of low calorie artificial sweeteners, which are being increasingly used in both low calorie and "normal" food products.
The APM molecule is a dipeptide composed of a highly hydrophilic aspartyl residue and a hydrophobic (phenylaianine methyl ester) entity and is zwitterionic at the aspartyl end. To date four polymorphic forms (IA, IB, IIA and IIB) of APM have been described (European Patent Application 0119837 B1, issued to Ajinomoto in 1988).
Compared to other artificial sweeteners APM has several advantages:
a) high sweetening power (300-400 that of sucrose as compared to 300 for saccharin and 30 for cyclamate); PA1 b) no after taste; and PA1 c) relatively good compatibility to human consumption (the acceptable daily intake in mg/kg/day of APM is 0-40 as compared to cyclamate 0-11, acesulfame 0-9 and saccharin 0-2.5). PA1 (a) an X-ray diffraction powder pattern (angles of diffraction) as set forth in FIG. 1b herein; PA1 (b) an FTIR spectrum as represented in FIGS. 3b and 4b herein; PA1 (c) TG/DTA and DSC patterns as represented in FIG. 5 appended hereto; PA1 (d) The NMR spectrum of the dissolved product is identical to the NHR spectrum of NUTRASWEET.RTM. as per FIG. 8a; and PA1 (e) improved dissolution kinetics as compared to commercial NUTRASWEET.RTM. aspartame as shown in FIG. 9 herein. PA1 (a) an X-diffraction powder pattern (FIG. 1c) which is distinctly different from the patterns of forms IA, IB, IIA, IIB as described in European patent No. 0119837B1 and from the pattern of APM III (FIG. 1b). PA1 (b) an FTIR spectrum as shown in FIGS. 3c and 4c PA1 (c) Thermogravimetric (TG and DTA) and differential scanning calorimetric patterns (FIG. 6) and PA1 (d) the H-NMR spectrum of the product dissolved in D2O (FIG. 8b).